Folding blade pocket knives

ABSTRACT

Two models of folding blade pocket knife both have a blade which is replaceable by opening the two halves of the handle, the blade being mounted on and interlocked with a rotatable disc for rotation as one unit. In both models, there is a storage for a spare blade. In one model, the handle parts have interlocking rear ends and are completely separable; the disc has a part annular peripheral spring tongue with an out-turned end engageable in a recess when the blade is extended, and there is a cantilever spring acting on the blade. In the other model, the handle parts are pivoted on an axis parallel to the folding axis of the blade; a spring-biased sliding latch member wedges the blade when the blade is extended and the latch member has to be pulled back to unwedge the blade.

nited States Patent 191 Gilbert FOLDING BLADE POCKET KNIVES [75]Inventor: Richard Gilbert, Sheffield, England [73] Assignee: StanleyTools Limited, Sheffield,

England [22] Filed: Nov. 29, 1972 [21] Appl. No.: 310,365

[30] Foreign Application Priority Data Dec. 9, 1971 Great Britain57297/71 [52] US. Cl. 30/157, 30/125 [51] Int. Cl B26b l/04 [58] Fieldof Search 30/125, 155, 156, 157, 30/330, 331, l58, 159, 160

[56] References Cited UNITED STATES PATENTS 994,226 6/1911 White 30/1571,478,260 12/1923 Sibley 1 30/157 1,495,449 5/1924 Sibley et a1. 30/160X 3,061,927 11/1962 Ludwigsdorf 1 1 30/156 3,509,627 5/1970 Gilbert30/125 3,641,667 2/1972 Leopoldi 30/156 X 1 Aug. 20, 1974 PrimaryExaminer-Al Lawrence Smith Assistant Examiner-J. C. Peters Attorney,Agent, or Firm-Prtuzman, Hayes, Kalb & Chilton [5 7 ABSTRACT Two modelsof folding blade pocket knife both have a blade which is replaceable byopening the two halves of the handle, the blade being mounted on andinterlocked with a rotatable disc for rotation as one unit. In bothmodels, there is a storage for a spare blade.

In one model, the handle parts have interlocking rear ends and arecompletely separable; the disc has a part annular peripheral springtongue with an out-turned end engageable in a recess when the blade isextended, and there is a cantilever spring acting on the blade.

in the other model, the handle parts are pivoted on an axis parallel tothe folding axis of the blade; a spring-biased sliding latch memberwedges the blade when the blade is extended and the latch member has tobe pulled back to unwedge the blade.

7 Claims, 35 Drawing Figures PATENTEBwszowm 3.829.967

SHEET 2 [IF 6 FIGS 12 |2b 12 FIGJO PATENTED M1920 1974 winnersPATENTEDwszomm 3,329,967

- SHEEI 50F e 1 FOLDING BLADE POCKET KNIVES This invention relates tofolding blade pocket knives.

BACKGROUND Folding blade pocket knives have been commonplace for verymany years. However, in the majority of cases there is no provision forreplacement of a worn out blade. Instead,-the entire knife has to bereplaced. One of the problems of making the blade replaceable is that ofpivotally mounting the blade so that it is firmly held relative to thehandle, particularly when in its operative, or extended, position.Another problem is spring-biasing the blade from an intermediateposition towards both fully extended and fully folded positions. Anotherproblem is the desirability of a detent or lock to keep the blade in itsextended position.

SUMMARY OF INVENTION According to one aspect of the invention there isprovided a pocket knife comprising a handle and a folding blade which isreplaceable and is spring assisted.

A folding blade pocket knife in accordance with the invention mayincorporate a semi-positive locking mechanism to hold the blade in theopen position.

A folding blade pocket knife in accordance with the invention mayinclude a stable intermediate position for safety in the blade closingaction.

A folding blade pocket knife in accordance with the invention may be onein which two halves of the handle are located at the rear end by aninterlock.

A folding blade pocket knife in accordance with the invention may be onein which a cavity between two halves of the handle provides storagespace for one or more spare blades, the blades being retained in placeby a spring.

According to another aspect of the invention there is provided a foldingblade pocket knife comprising a handle in which a blade is pivotallymounted so that the blade can be folded into a storage position with acutting edge of the blade inside the handle and can be unfolded into anoperative position, the handle being in a plurality of parts releasablysecured together in such a manner that when released the parts can beseparated to enable removal and replacement of the blade.

The knife may comprise, inside the handle, a rotatable member, such forexample as a disc, the member being formed to engage the bladeinterlockingly so that the blade and the rotatable member pivot as one.

In one embodiment of the invention, such a rotatable member includes aresiliently deformable portion which is engageable with part of thehandle to hold or tend to hold the blade in its operative position andthe knife includes a cantilever spring engageable with the blade and/orthe rotatable member to bias the blade from an intermediate positioneither to the storage position or to the operative position depending onwhich way the blade is moved by the user.

In another embodiment of the invention the knife I comprises aspring-biased latch member which must be moved against the spring biasto release the blade from the operative position and enable it to befolded into the storage position. The latch member is slidably mountedwith part thereof inside the handle adapted to wedge the blade in itsoperative position under the spring bias. The knife includes storagewithin the handle for a spare blade, the storage being formed partly bythe latch member, part of which forms a spring to engage the spare bladeand, when the handle parts are separated, to move the spare bladeoutwardly so that the spare blade can readily be withdrawn from storage.The handle parts are separable by pivoting one relative to the otherwhen the first-mentioned blade is in the operative position, one of thehandle parts engaging the latch member to enwedge the blade so that theblade can be removed and replaced.

The invention will be described by way of examples with reference to theaccompanying drawings.

IN THE DRAWINGS:

FIG. 1 is a side elevation of one embodiment of the invention;

FIG. 2 is a plan view of the embodiment shown in FIG. 1:

FIG. 3 is a plan view of the embodiment shown in FIGS. 1 and 2 but withone handle part removed and with the spring position shown in phantomlines;

FIG. 4 is a side elevation of one part of the handle of the embodimentshown in FIGS. 1 to 3;

FIG. 5 is a plan view of the handle part shown in FIG.

FIG. 6 is a side elevation of another part of the handle of theembodiment shown in FIG. 1;

FIG. 7 is a plan view of the handle part shown in FIG. 6, together withthe spring;

FIG. 8 is an enlarged section on line X X in FIG. 7;

FIG. 9 is a side elevation of a cantilever spring of the embodimentshown in FIG. 1;

FIG. I0 is a plan view of the spring shown in FIG. 9;

FIG. 11 is a side elevation of a rotatable member in the form of a discof the embodiment shown in FIG. 1;

FIG. 12 is a plan view of the disc shown in FIG. 11;

FIG. 13 is an end elevation of the disc shown in FIG. 11;

FIG. 14 is a plan view of another embodiment of the invention;

FIG. 15 is a plan view of the embodiment shown in FIG. 14 with handleparts shown separated;

FIG. 16 is a diagrammatic illustration of the embodiment shown in FIG.14 with one handle part removed;

FIG. 17 is a scrap view of the embodiment of FIG. 14 showing the bladewedged in its operative position;

FIG. 18 is another scrap view of the embodiment of FIG. 14 showing theblade in its storage position;

FIG. 19 is a sectional view in side elevation corresponding to FIG. 15with the handle parts shown separated and a spare blade sprung upwardlyto facilitate removal from a storage space;

FIG. 20 is a sectional-view in side elevation corresponding to FIG. 14with the handle parts shown closed together as in FIG. 14;

FIGS. 21 to 25 illustrate one body part of the embodiment shown in FIG.14, being a section on line A-A (in FIG. 22), a plan view, an invertedplan view and sections on lines B-B and C-C (in FIG. 22) respectively;

FIGS. 26 to 30 illustrate another body part of the embodiment shown inFIG. 14, being a section on line DD (in FIG. 27), an inverted plan view,a plan view and sections on lines E-E and F-F (in FIG. 27) respectively;and

FIGS. 31 to 35 illustrate a latch member of the em bodiment shown inFIG. 14, being two opposite side elevations, a plan view, an invertedplan view and a section on line GG in FIG. 34 respectively.

DESCRIPTION OF PREFERRED EMBODIMENTS The embodiment shown in FIGS. 1 to13 is a folding blade pocket knife 1 comprising a handle 2 in which ablade 3 is pivotally mounted so that the blade 3 can be folded into astorage position (not shown) with a cutting edge 4 of the blade 3 insidethe handle 2 and can be unfolded into an operative position as shown inFIGS. 1 and 2, the handle being in two parts 5 and 6 releasably securedtogether by means inter alia of a screw 7 in such a manner that, whenreleased, the handle parts 5 and 6 can be separated to enable removaland replacement of the blade 3.

The knife 1 comprises, inside the handle 2, a rotatable member 8 in theform of a disc formed to engage the blade 3 interlockingly so that theblade 3 and the disc 8 rotate as one. The disc 8 includes a resilientlydeformable portion 9 in the form of a part annular peripheral tonguehaving at an outer end thereof a lateral projection 10 which isengageable with a recess 11 in the handle part 5 to hold or tend to holdthe blade 3 in its operative position. The knife 1 includes aprestressed cantilever spring 12 having one part 12a engaging handlepart 6 and having a part 12b engageable with a portion 13 of the disc 8,to exert a bias on the disc 8 and thus indirectly on the blade 3 throughdisc portion 13 both when (as shown in FIG. 3) the blade 3 is in itsoperative position and when the blade 3 is folded into its operativeposition and when the blade 3 is folded into its storage position. Thedisc portion 13 engages a keyhole-shaped slot in the blade 3 so that theblade 3 and the disc 8 rotate as one.

The body portion 5 is formed with abutments 14 and 15 for the blade 3for the operative and storage positions respectively of blade 3.

The cantilever spring 12 is formed with a detent 16 in which the discportion 13 rests in an intermediate, stable, position of the blade 3.The spring 12 biases the blade 3 either to the storage position or tothe operative position depending on which way the blade 3 is moved bythe user.

The handle parts 5 and 6 have at their ends interlocking portions 17 and18 respectively to secure the parts 5 and 6 releasably together incombination with the screw 7.

The embodiment shown in FIGS. 14 to 35 is preferred to that of FIGS. 1to 13 and is a folding blade pocket knife 20 comprising a handle 21 inwhich a blade 22 is pivotally mounted so that the blade 22 can be foldedinto a storage position, (FIG. 18,) with a cutting edge 23 of the blade22 inside the handle 21 and can be unfolded into an operative position,(FIGS. l4, l6 and 17,) the handle 21 being in two parts 24 and 25releasably secured together-by means of a cross-head screw 26 which isnot intended to be undone by the user and by means ofa coin-slot" screw27 which can be undone by insertion of a coin (not shown) in slot 28 torelease the handle parts 24 and 25 so that they can be separated asshown in FIG. 15 to enable removal and replacement of the blade 22.

The knife 20 comprises, inside the handle 21, a rotatable disc 29 formedwith a projection 29a (exactly like projection 13 of disc 8 in theembodiment of figures 1 to 13) to engage a keyhole slot in the blade 22interlockingly so that the blade 22 and the disc 29 rotate as one.

The knife 20 also comprises a spring-biassed latch member 30 which mustbe moved (rightwards as seen in FIGS. 16 and 17) against the spring biasto release the blade 22 from the operative position and enable it to befolded into the storage position. The latch member 30 is slidablymounted with an end part 31 thereof outside the handle 21 for pullingthe latch member 30 against the spring bias and with the remaining part32 of latch member 30 inside the handle. An inclined surface 33 at theopposite end of the latch member 30 is engageable with a similarlyinclined surface 34 of the disc 29 inside the handle 21, as shown inFIG. 17, to wedge the blade 22 in its operative position under thespring bias. The spring bias is provided by a helical compression spring35 seated on a projection 36 of latch member 30 and engaging aprojection 37 of handle part 24.

The knife 20 includes storage within the handle 21 for a spare blade 38,(FIGS. 16, 19 and 20 only). The storage is formed partly by the latchmember 30, a part 39 of which (not shown in FIGS. 16 and 18) forms aspring to engage the spare blade 28, and, when the handle parts 24 and25 are separated as shown in FIG. 15, to move the spare blade 28outwardly as shown in FIG. 19, pivoting the spare blade 28 about afulcrum, so that the spare blade 28 can readily be withdrawn fromstorage. The latch member 30 has a triangular recess 40 (FIG. 34) forthe pointed end 41 (FIG. 16) of the spare blade 38 and has a boss 42 forthe keyhole slot 43 in the spare blade 38. A tongue 44 at the end ofmember 30 yieldably holds the blade 22 in position on the disc 29 Thehandle parts 24 and 25 are separated by pivoting part 25 relative topart 24 about a pivot formed by the boss 45 when the blade 22 is in theoperative position as shown in FIG. 15. The handle part 25 engages theend part 31 of latch member 30, moving the latch member 30 to the rightas shown in FIG. 15 to disengage surfaces 33 and 34 and hence unwedgethe blade 22 so that the blade 22 can be removed and replaced.

The handle part 24 comprises bosses 45 and 46 for screws 26 and 27respectively, boss 45 being initially unthreaded, (screw 26 being aself-tapping screw), whilst boss 46 is internally threaded and alsoserves to locate the blade 22 and disc 29. The handle part 24 alsocomprises an abutment 47 for the blade 22 in its operative position andside flanges 48 and 49 for slidably guiding the latch member 30.

The handle part 25 comprises apertures 50 and 51 for the boss 45 andscrew 27 respectively, recesses 53 and 52 for the heads of screws 26 and27 respectively and a projection 54 to serve as an abutment for theblade 22 in its storage position.

The latch member 30 also has an elongate aperture 55 for boss 45 and thespring tongue 44.

When opening blade 22 from the storage position, FIG. 18, a surface 56of disc 29 pushes the latch member 30 rightwardly as seen in FIG. 18, sothat the latch member 30 need not be handled to unfold the blade 22.

I claim:

1. A folding blade pocket knife, comprising: a handle which is formed ofa plurality of parts; means for releasably securing said parts together;a blade, part of which defines a cutting edge; means for pivotallymounting the blade in the handle so that the blade can be unfolded intoan extended position and folded into a stored position when the handleparts are secured together; the handle having a storage space thereinfor at least the cutting edge-defining part of the blade when saidhandle parts are secured together and when the blade is in the storedposition; means for preventing removal of the blade from the handle whensaid handle parts are secured together and permitting separation of theblade from all said parts of the handle when said handle parts arereleased from being secured together;

latching means for latching the blade in its extended position, saidlatching means including a latch member movably mounted inside thehandle for movement between a latching position and an unlatchingposition, spring means for biasing said latch member towards saidlatching position, manually operable means for moving said latch memberagainst the spring bias to the unlatching position; and storage withinthe handle for a spare blade, the storage being formed partly by acavity in the latch member, part of the latch member forming a spring toengage the spare blade and, when the handle parts are separated, to movethe spare blade outwardly, whereby the spare blade can readily bewithdrawn from storage.

2. A folding blade pocket knife, comprising; a handle which is formed ofa plurality of parts; means for releasably securing said parts together;a blade, part of which defines a cutting edge; means for pivotallymounting the blade in the handle so that the blade can be unfolded intoan extended position and folded into a stored position when the handleparts are secured together; the handle having a storage space thereinfor at least the cutting edge-defining part of the blade when saidhandle parts are secured together and when the blade is in the storedposition; means for preventing removal of the blade from the handle whensaid handle parts are secured together and permitting separation of theblade from all said parts of the handle when said handle parts arereleased from being secured together; latching means for latching theblade in its extended position, said latching means including a latchmember movably mounted inside the handle for movement between a latchingposition and unlatching position, spring means for biasing said latchmember towards said latching position, manually operable means formoving said latch member against the spring bias to the unlatchingposition; said handle parts being pivotally connected together and beingseparable by pivoting one relative to the other when the blade is in itsextended position, one of the handle parts including means for engagingthe latch member to unlatch the blade so that the blade can be removedand replaced.

3. A folding blade pocket knife comprising: a handle which is in twoseparable parts; a blade, part of which defines a cutting edge; meansfor pivotally mounting the blade inside the handle folding into astorage position, with the cutting edge inside the handle, and forunfolding the blade into an operative position, with the cutting edgeoutside the handle; means for releasably securing the handle partstogether whereby, when released, said handle parts can be separated;said means for pivotally mounting the-blade comprising a rotatable discmember inside the handle; said blade and rotatable disc member havinginterlockingly engageable portions whereby the blade and rotatable discmember are rotatable as one unit and are separable from each other; therotatable disc member including a resiliently deformable portion in theform of a part-annular peripheral tongue having at an outer end thereofa portion which is engageable in a recess in the handle, whereby theblade can be retained in said operative position; and a prestressedcantilever spring having one part engaging the handle and having anotherpart engageable with a portion of the disc member to exert a bias on thedisc member and hence on the blade both when the blade is in itsoperative position and when the blade is in its storage position; thehandle part securing means comprising a screw-threaded member andmutually interlocking portions of the two handle parts, whereby when thehandle parts are separated the blade can be removed and replaced.

4. A folding blade pocket knife as claimed in claim 3 wherein thecantilever spring is formed with a detent which is engageable by part ofthe disc member when the disc member and the blade are in a positionintermediate the storage position and the operative position, wherebythe blade and the disc member are stable in the intermediate position.

5. A folding blade pocket knife comprising: a handle which is in firstand second separable parts; a blade, part of which defines a cuttingedge; means for pivotally mounting the blade inside the handle forfolding about an axis into a storage position, with the cutting edgeinside the handle, and for unfolding the blade into an operativeposition, with the cutting edge outside the handle; means for releasablysecuring the handle parts together whereby, when released, said handlecan be opened; said means for pivotally mounting the blade comprising arotatable disc member inside the handle; said blade and rotatable discmember having interlockingly engageable portions whereby the blade androtatable disc member are rotatable as one unit and are separable fromeach other; a latch member slidably mounted in said first handle partand having a first part outside the handle and a second part inside thehandle, said second part of the latch member having a surface which isinclined at an acute angle relative to the direction of sliding of thelatch member; said disc member having a surface so arranged as to beengageable by said surface of the latch member when the blade isunfolded into its operative position; and means for springbiasing thelatch member in such a direction as to urge said surface therof intoengagement with said surface of the disc member, whereby to wedge theblade in its operative position; the handle part securing meansincluding means pivotally connecting the handle parts together with apivot axis parallel to the folding axis of the blade, whereby the handlecan be opened by rela tive pivoting of the two handle parts; the secondhandle part including a portion which is engageable with the latchmember to move the latch member against the spring bias when the handleis opened by said relative pivoting of the two handle parts, whereby theblade is unwedged and can be removed and replaced.

6. A folding blade pocket knife as claimed in claim 5 and includingstorage for a spare blade, part of the latch member forming a springwhich is engageable with the spare blade to move the spare bladeoutwardly when the handle is opened.

7. A folding blade pocket knife comprising: a handle which is in firstand second separable parts; a blade, part of which defines a cuttingedge; means for pivotally mounting the blade inside the handle forfolding about an axis into a storage position, with the cutting edgeinside the handle, and for unfolding the blade into an operativeposition, with the cutting edge outside the handle; said means forpivotally mounting the blade comprising a rotatable disc memberjournaled on said blade pivotal mounting means; said blade and rotatabledisc member having interlockingly engageable portions whereby the bladeand rotatable disc member are rotatable as one unit and are separablefrom each other; a latch member slidably mounted in said first handlepart and having a first part outside the handle and a second part insidethe handle, said second part of the latch member having a latchingsurface disposed generally in the direction of sliding of the latchmember; said disc member having a surface so arranged as to beengageable by said latching surface of the latch member when the bladeis unfolded into its operative position; and means for spring-biasingthe latch member in such a direction as to urge said surface thereofinto engagement with said surface of the disc member to lock the bladein its operative position.

1. A folding blade pocket knife, comprising: a handle which is formed ofa plurality of parts; means for releasably securing said parts together;a blade, part of which defines a cutting edge; means for pivotallymounting the blade in the handle so that the blade can be unfolded intoan extended position and folded into a stored position when the handleparts are secured together; the handle having a storage space thereinfor at least the cutting edge-defining part of the blade when saidhandle parts are secured together and when the blade is in the storedposition; means for preventing removal of the blade from the handle whensaid handle parts are secured together and permitting separation of theblade from all said parts of the handle when said handle parts arereleased from being secured together; latching means for latching theblade in its extended position, said latching means including a latchmember movably mounted inside the handle for movement between a latchingposition and an unlatching position, spring means for biasing said latchmember towards said latching position, manually operable means formoving said latch member against the spring bias to the unlatchingposition; and storage within the handle for a spare blade, the storagebeing formed partly by a cavity in the latch member, part of the latchmember forming a spring to engage the spare blade and, when the handleparts are separated, to move the spare blade outwardly, whereby thespare blade can readily be withdrawn from storage.
 2. A folding bladepocket knife, comprising; a handle which is formed of a plurality ofparts; means for releasably securing said parts together; a blade, partof which defines a cutting edge; means for pivotally mounting the bladeiN the handle so that the blade can be unfolded into an extendedposition and folded into a stored position when the handle parts aresecured together; the handle having a storage space therein for at leastthe cutting edge-defining part of the blade when said handle parts aresecured together and when the blade is in the stored position; means forpreventing removal of the blade from the handle when said handle partsare secured together and permitting separation of the blade from allsaid parts of the handle when said handle parts are released from beingsecured together; latching means for latching the blade in its extendedposition, said latching means including a latch member movably mountedinside the handle for movement between a latching position andunlatching position, spring means for biasing said latch member towardssaid latching position, manually operable means for moving said latchmember against the spring bias to the unlatching position; said handleparts being pivotally connected together and being separable by pivotingone relative to the other when the blade is in its extended position,one of the handle parts including means for engaging the latch member tounlatch the blade so that the blade can be removed and replaced.
 3. Afolding blade pocket knife comprising: a handle which is in twoseparable parts; a blade, part of which defines a cutting edge; meansfor pivotally mounting the blade inside the handle folding into astorage position, with the cutting edge inside the handle, and forunfolding the blade into an operative position, with the cutting edgeoutside the handle; means for releasably securing the handle partstogether whereby, when released, said handle parts can be separated;said means for pivotally mounting the blade comprising a rotatable discmember inside the handle; said blade and rotatable disc member havinginterlockingly engageable portions whereby the blade and rotatable discmember are rotatable as one unit and are separable from each other; therotatable disc member including a resiliently deformable portion in theform of a part-annular peripheral tongue having at an outer end thereofa portion which is engageable in a recess in the handle, whereby theblade can be retained in said operative position; and a prestressedcantilever spring having one part engaging the handle and having anotherpart engageable with a portion of the disc member to exert a bias on thedisc member and hence on the blade both when the blade is in itsoperative position and when the blade is in its storage position; thehandle part securing means comprising a screw-threaded member andmutually interlocking portions of the two handle parts, whereby when thehandle parts are separated the blade can be removed and replaced.
 4. Afolding blade pocket knife as claimed in claim 3 wherein the cantileverspring is formed with a detent which is engageable by part of the discmember when the disc member and the blade are in a position intermediatethe storage position and the operative position, whereby the blade andthe disc member are stable in the intermediate position.
 5. A foldingblade pocket knife comprising: a handle which is in first and secondseparable parts; a blade, part of which defines a cutting edge; meansfor pivotally mounting the blade inside the handle for folding about anaxis into a storage position, with the cutting edge inside the handle,and for unfolding the blade into an operative position, with the cuttingedge outside the handle; means for releasably securing the handle partstogether whereby, when released, said handle can be opened; said meansfor pivotally mounting the blade comprising a rotatable disc memberinside the handle; said blade and rotatable disc member havinginterlockingly engageable portions whereby the blade and rotatable discmember are rotatable as one unit and are separable from each other; alatch member slidably mounted in said first handle part and having afirst part outside the handle and a second paRt inside the handle, saidsecond part of the latch member having a surface which is inclined at anacute angle relative to the direction of sliding of the latch member;said disc member having a surface so arranged as to be engageable bysaid surface of the latch member when the blade is unfolded into itsoperative position; and means for spring-biasing the latch member insuch a direction as to urge said surface therof into engagement withsaid surface of the disc member, whereby to wedge the blade in itsoperative position; the handle part securing means including meanspivotally connecting the handle parts together with a pivot axisparallel to the folding axis of the blade, whereby the handle can beopened by relative pivoting of the two handle parts; the second handlepart including a portion which is engageable with the latch member tomove the latch member against the spring bias when the handle is openedby said relative pivoting of the two handle parts, whereby the blade isunwedged and can be removed and replaced.
 6. A folding blade pocketknife as claimed in claim 5 and including storage for a spare blade,part of the latch member forming a spring which is engageable with thespare blade to move the spare blade outwardly when the handle is opened.7. A folding blade pocket knife comprising: a handle which is in firstand second separable parts; a blade, part of which defines a cuttingedge; means for pivotally mounting the blade inside the handle forfolding about an axis into a storage position, with the cutting edgeinside the handle, and for unfolding the blade into an operativeposition, with the cutting edge outside the handle; said means forpivotally mounting the blade comprising a rotatable disc memberjournaled on said blade pivotal mounting means; said blade and rotatabledisc member having interlockingly engageable portions whereby the bladeand rotatable disc member are rotatable as one unit and are separablefrom each other; a latch member slidably mounted in said first handlepart and having a first part outside the handle and a second part insidethe handle, said second part of the latch member having a latchingsurface disposed generally in the direction of sliding of the latchmember; said disc member having a surface so arranged as to beengageable by said latching surface of the latch member when the bladeis unfolded into its operative position; and means for spring-biasingthe latch member in such a direction as to urge said surface thereofinto engagement with said surface of the disc member to lock the bladein its operative position.